Hi managers,
Last week I posted a question with respect to the strange
behaviour of NFS UDP traffic on a 4.0D system with two network
interfaces (namely that the outgoing NFS traffic does not
obey static routes, while all the rest of IP traffic does).
Several people offered their advice on configuration
settings on the server and clients I might have overlooked
(I didn't), but the two most interesting replies came from
Claude Scarpelli (claude_at_genoscope.cns.fr) and Georg Tasman
(georg.tasman_at_db.com), who indicated that they observed
several problems with routing of NFS traffic, but know of
no solution to these problems.
The Claude's reply is particularly illuminating (and more
than a bit scary - at least to me) and is appended at the
end of this message. The conclusion I make out of my query
is that we are lucky indeed our setup works as well as it
does - even if it does not work for NFS...
Thanks to everybody,
/Serge.P
---- Claude Scarpelli's message starts here
I'm not sure that we have the same problem, but I can say that routing
in 4.0D kit 3 is broken. Since we upgrade our systems (NFS clients) to
this version, we discover various routing problems. One of them
reminds us something that has been corrected by kit BL6 of 4.0B
(OSFPAT00026900410), where routes learned by ICMP redirects may be,
under some circumstances, ignored by the kernel (and especially the
NFS code).
Here is a list of network problem we see in 4.0D:
- routing table as reported by netstat -r may not be the one used by
the kernel NFS code.
- routes learned by ICMP Redirects are not always written in the
routing table (such routes are flagged with the letter D in the
output of netstat -r)
- When ICMP Redirect routes are written in the routing table, they do
not expire. Since the default configuration of gated gives ICMP
Redirect routes a better preference over RIP learned routes, it may
lead to non optimal routing table.
- We are running gated (RIPv1). Sometime, routes (learned via RIP) may
desappears from the routing table (as reported by netstat -r). Using
debug option of gated, we see that gated is not responsible for
these additions and deletions.
All of this result in NFS datagrams being sent to the wrong
destination (the default router), leading to a lot of ICMP Redirects
messages.
We have a case open on these subjects.
Received on Mon Mar 08 1999 - 17:28:31 NZDT